Pain sensitivity does not differ between obese and healthy weight individuals

There is emerging evidence suggesting a relationship between obesity and chronic pain. We investigated whether pain-free obese individuals display altered pain responses to acute noxious stimuli, thus raising the possibility of greater pain sensitivity and potential susceptibility for chronic pain development. Psychophysical and anthropometric data were collected from 39 individuals with an obese body mass index (BMI) classification (BMI[≥]30) and 40 age/sex-matched individuals of a healthy BMI (BMI<24.9). Since BMI may be an inaccurate index of obesity, additional anthropometric parameters of central adiposity, and percent body fat (BF%) were examined. Pain responses to supra-threshold noxious heat and cold stimuli were examined. Subjects provided pain intensity and unpleasantness ratings to noxious heat (49{degrees}C) applied at varying durations (5s, 12s, 30s) and locations (ventral forearm/lower leg). Cold pain ratings, thresholds, and tolerances were obtained following immersion of the hand in a cold-water bath (0-2{degrees}C). Between-group differences in pain responses, as well as relationships between pain responses and obesity parameters were examined. Importantly, confounds that may influence pain such as anxiety, depression, impulsivity, sleepiness, and quality of life were assessed. No between-group differences in pain sensitivity to noxious heat and cold stimuli were found. After controlling for sex, no relationships were found between BMI, central adiposity, or BF% and pain responses to noxious heat or cold stimuli. These results indicate that obesity, BF%, and central adiposity have little influence on pain sensitivity in obese individuals. Accordingly, it is unlikely that obesity alone increases susceptibility for chronic pain development via amplification of nociceptive processes.